From: "Christian König" <deathsimple@vodafone.de>
To: "Rafał Miłecki" <zajec5@gmail.com>,
dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [TIP] Catalyst / fglrx and DVI to HDMI adapters (audio)
Date: Mon, 07 Oct 2013 10:51:01 +0200 [thread overview]
Message-ID: <525275F5.30309@vodafone.de> (raw)
In-Reply-To: <CACna6rzx_WNDTqf+bGj-Xpi3Aruak-XU+XEPXCVY8_yqDvSvRA@mail.gmail.com>
Am 07.10.2013 10:06, schrieb Rafał Miłecki:
> For the last few days it was I was testing fglrx on various cards to
> trace HDMI setup. One thing that was killing me was no HDMI audio when
> using some generic/cheap DVI to HDMI adapter with my HD 4850.
>
> I started digging and it has appeared to be common problem when using
> Catalyst / fglrx. Windows users were also experiencing this problem,
> without any known workaround.
>
> I've found one explanation by droidhacker:
> http://phoronix.com/forums/showthread.php?23451-HDMI-Audio-with-fglrx&p=124891#post124891
>> If that is the case, you need to be aware that AMD sells a couple of PROPRIETARY adapter plugs, which fglrx can DETECT in order to decide whether or not to enable HDMI audio.
> That sounded weird, I didn't believe that. There wasn't any
> explanation how it's handled, I couldn't imagine how fglrx can "talk"
> to the simple adapter. Overall it should just map the PINs, not
> include any logic!
>
> But today I've found another discussion:
> http://www.avsforum.com/t/1080627/atis-magic-dvi-to-hdmi-dongle
>
> That finally explains what is happening. So it appears that ATI's
> proprietary adapter include some tiny I2C protocol that allows
> identifying them! It seems that Catalyst / fglrx uses some simple I2C
> talk to check if the adapter is made by ATI and allows or refuses to
> use HDMI mode.
> That also explains why radeon driver never had any problems with audio
> over DVI, no matter what adapter was used.
>
> Another ATI/fgllx mystery explained ;)
Why didn't you just asked me?
I've figured this out over five years ago by applying brute force to one
of the "magic" DVI->HDMI adapters that came with my original RV635. And
it indeed contains an extra EEPROM on the I2C bus ;)
Cheers,
Christian.
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next prev parent reply other threads:[~2013-10-07 8:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-07 8:06 [TIP] Catalyst / fglrx and DVI to HDMI adapters (audio) Rafał Miłecki
2013-10-07 8:51 ` Christian König [this message]
2013-10-07 8:58 ` Rafał Miłecki
2013-10-07 9:22 ` Christian König
2013-10-07 22:14 ` Dieter Nützel
2013-10-08 8:29 ` Christian König
2013-10-09 22:40 ` Matt Sealey
2013-10-10 9:30 ` Christian König
2013-10-10 14:47 ` Matt Sealey
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